Tensei Seijo wa Akujo ni Naritai

Kokomi, a hard-working office worker, collapses during overtime and wakes up to find herself as Cocoash, the protagonist of a certain story. Despite being shunned by her family and treated coldly by her fiancé, she continues to work hard and do her job without giving up - and eventually becomes known as a saint, which is what her true life was meant to be...

But no more goody-two-shoes! A corporate slave office worker's plan to redo her life!!

(Source: Akita Shoten, translated)